The neurotoxin, 6-hydroxydopamine(6-HD) and its quinone will be, using selected electrochemical techniques, reacted with various biological nucleophilic molecules in solution. Reaction kinetics and the chemical structure of the products will be determined. 6-HD and its quinone will also be reacted, in vitro with nerve ending particles (synaptosomes) and synaptic plasma membrane fragments isolated from rat forebrain. With respect to the synaptosomes, the effects of the neurotoxin on uptake and release of radiolabelled catecholamine neurotransmitters, dopamine and norepinephrine, synaptic plasma fragments will be elucidatd by polyacrylamide gel electrophoresis. Using the data from the above experiments, an experimental protocol will be established to determine if, and under what conditions, normal brain catecholamines and their metabolites can exhibit neurotoxic effect similar to those of 6-HD.